# 字符串

m="abcdefghijklmnopqrstuvwxyz"
print(m[3:6:2])
print(m[3:6])

v="0123456789"
# 左闭右开
print(v[3:6])
# 开始的地方有，结算-1
print(v[3:6:2])
print(v[6:3:-1])